The last great conflict to be conducted on both sides of a large waterway brought out:
the slowness in construction and the long periods necessary for using standard pontoon bridges, even by personnel very well trained and highly motivated in a combat situation, and
the very great fragility and vulnerability of these pontoon bridges which, detected, monitored and perfectly pinpointed by satellite, were systematically the target of long-range weapons at the most opportune time to cause maximum damage to equipment and to troops.
It follows from these findings that it is very advantageous to have, for crossing a waterway, a number of amphibious devices, of great operational efficiency, which are incomparably less vulnerable than pontoon bridges because of their mobility.
There is known a type of vehicle having a hull, equipped with retractable, motorized wheels for land movement, this hull forming a float for crossing stretches of water, and being equipped on its front walls with two series of hinged ramps which, when in unfolded position, extend the upper face of the hull and with it delimit the loading plane. The longitudinal side walls of the hull carry inflatable auxiliary floats for increasing the buoyancy of the vehicle when it is used as a ferry. In these vehicles, the inflatable auxiliary floats have a length less than that of the hull thereby leaving a space between each end of each auxiliary float and the adjacent one of the neighboring float carried by one of the vehicle ramps. This space is disadvantageous as the water can rush thereinto and thereby impair the stability of the vehicle.
Moreover, this type of vehicle generally includes aquatic propulsion means consisting of directable propellers mounted on telescopic supports placed vertically at its front walls. The good functioning of these propellers requires the presence of recesses and tunnels in the hull and spaces between the hull and the floats. This results in a considerable reduction of the volume of the hull, limiting its buoyancy, increasing the draft, and creating difficulties in access to the driver's stations, by requiring doors placed in the lateral walls. Furthermore, the propellers are very vulnerable, increase the draft of the vehicle, and impose shapes on the keel which allow only a mediocre passage in the water, considering the breaks in continuity between the various floating parts.
French Pat. No. 2,500,504 discloses a motorized bridge whose central element is equipped with two water jet propulsion devices which, in comparison with propeller devices, offer the advantage of considerably reduced bulk, less vulnerability, and finally, much less discomfort in the driver's station. The device still suffers from the other disadvantages of such vehicles discussed above.